Inertial Embedded Fronts

Abstract

Many recent observations have described fronts in the interior of the ocean at locations far away from any lateral boundaries. Some of these fronts are observed to be associated with considerable mass transports, which suggests that they participate importantly in setting the water mass structure of the ocean interior, and represent considerable local departures from linear Sverdrup dynamics. In this paper, a simple analytic theory of interior fronts is developed. The main features of this theory are that the fronts are highly inertial and anisotropic, and reside on the edge of a somewhat larger scale interior inertial recirculation. The recirculation is taken to be modonlike; the dynamic height difference across the edge of the recirculation supports an interior jet, which is clockwise around the edge of the recirculation and carries water from the subpolar into the subtropical gyre. Unlike in previous theories of interior fronts, all of the transports, both in the large-scale and the fronts, are ?anomalous? and in excess of any wind-driven transport. The fronts themselves represent interior, deformation-scale boundary layers, which are necessary to smoothly join the baroclinic parts of the inertial recirculation and the sluggish Sverdrup zones. The authors speculate on the role of these dynamics in the LDE jet.